replay remaining time displays total duration of recording instead

Input 7 & 8 are my two replay channels

Set a button text to `$(vmix:input_7_remaining_ss)`

**Expected**
Displays remaining duration of current replay event. If the event is 5 seconds long, expect the button to count down from 5 to 0.

**Actual**
Displays total recorded duration. Pause recording and time stops ticking. Start recording again and time starts ticking again.
